I played a demo earlier called Ninja Discount Warehouse that was just released yesterday. It was made as part of the Valve VR jam a few months ago by William Manning and Eli Gorman. Using only the Oculus Rift, you jerk your head down to pick up barrels, and then jerk your head either left or right to throw those barrels at incoming ninjas. It's an interesting demo that uses only the motion sensors in the headset itself, though I don't think I would want to play something like that for too long as there is a small gap between my nose and the headset, so whenever I jerk my head quickly the headset will hit my nose and it'll hurt a little. It worked a lot better than I would expect, however. It's more fun when you start picking up as many objects as you can before flinging them all in one, massive push. I recommend checking it out briefly for the novelty of doing these actions with just your head.